I need some help on figuring out how to wire up am LM386 amp for simple audio.

I have searched and found many different approaches/methods..

and I 'thought' I had it working.. but unfortunately.. I get no sound. =( (not sure if I have something wrong? (or if I need some resistors or whatever to create what I read is called a low filter pass for freq.)

I am very new to this, so please understand if you use phrases or terminology that someone with experience in this field would understand,.... I wont be able to use your advice/help! =)

I did give it a shot..and made a diagram on how I have things wired up..

are you 'sure' anything is needed between pins 1 & 8? I have seen many, including the layout Im trying to copy/mimic, that have NOTHING on the pins 1 & 8

my SOUND INPUT is actually coming from a PIC chip... that has a pre-define/flashed firmware on it.. and that specific pin is the SND output pin.

I tested my 'code'.. with a RadioShack, mini amplified speaker.. and the sound 'does' play.. albeit a bit poorly.. (if volume its way up it sounds like crap!. if volume is mid-way it low/soft..but sound ok/better as far as clarity).. by bypassing the AMP all together.. and plugging the RS mini amp speaker to GNS rail and the SND pin on the pic directly..

this I dont understand:"Can you confirm you have connected a second (ground) connection between your sound source and the amplifier circuit ground."

**on my diagram.. you mean the green trace needs to have a 'branch' off to GND?

Also.. should be default GAIN of 20 without anything on pins 1 & 8..right? is that not enough to 'do' anything? The board/pcb I have in my hand doesnt have anything on the 1 & 8 pins..

I 'can' add that if you are telling me that is the error/problem? (but that should only have to do with volume......correct? not working or not working at all?

I have NOT tried a higher supply voltage than 5v... I can try to jump/use my V++ input rail.. (before my 5v vRegulator).. which is controlled by my PSU.. (usually at like 7.4v..to mimic a li-ion pack I'll eventually be using)

No.. . I am NOT sure things are wired correctly... I 'am' sure (however) that it is wired as I have re-created in my diagram above. =)

I do have a digital multi-meter, but am not sure where/what pins I would meter to check things out..

I know my code and PIC is wired up correctly.. as my LEDs and 'animation' (etc..etc) is working fine.. just no 'audio' when I hook my speaker up to the 'amp'..

(again bypassing that and going directly with a pre-amp speaker... using the sound input/green trace and GND works fine.. although a bit 'soft'..)

Signals from a source to an amplifier are fed via 2 wires, usually a coaxial cable, one (the core) carries the variable signal and the other (the outer shield) is the reference point - usually ground. However for experimental purposes a pair of separate wires will be good enough.

So from your PIC circuit you should have 2 wires, one feeding the signal to the amplifier input and the other, the ground reference connected to your amplifier ground.

Your circuit doesn't show how you connect the signal from the PIC circuit to the potentiometer. This circuit must be connected via an isolation capacitor. The value is determined by the input impedance of your amplifier, which in this case is the value of the potentiometer. I'd suggest a 10uF as a starting point. The capacitor is a DC blocker which permits only the AC signal tyo get through to the OPamp. Without this blocker the DC level of the PIC circuit may be biasing the OPamp into a ground or VCC saturated state and so prevent it reacting to the AC signal.

I take it you have also tried adjusting the pot to ensure it isn't set to feed 0% into the amplifier input.

I'm not certain about the dc-blocking cap in the input line as mentioned, but I re-worked your dwg --

The 5V is marginal, V_in may be better (provided it isn't > v_max, and doesn't drag down your supply during loud/hi-volume periods -- something to "worry" about later.)Make sure that it's the pot's "wiper" going to the amp_in.The gain programming cap (pin 1 & pin8) is probably a good idea (won't hurt.)

"Who is like unto the beast? who is able to make war with him?"When all else fails, check your wiring!

thanks again for keeping with the thread! (its hard being new and waiting DAYS to trouble shoot a simple LM386 circuit!) haha

I'l add in the 10uF cap and see what happens..

oops..sorry yes that trace SHOULD have have the label to GND like the others..

knowing that now.. is my original wiring diagram correct then? if not.. Im still missing how what you did is electronically different?if it is ok.... then thanks for clarifying for me. =)

I think the PIC project must be using some PWM to emulate sound? (not sure as the firmware is closed/isnt mine).... and there is no DAC or anything.. (but I dont need/want super quality sound.. average FX type sounds are fine enough)

adding cap now!

update:adding the GAIN cap.. 'made it work'.. must have not been enough signal to play/hear anything?

Well Im glad that part is at least tackled. =)

Thanks everyone for sticking with me/this.

Now.. Id like to learn how to make it better sounding? Is there where all the resistors/caps and stuff used to make 'filters' come into play?

I understand the general idea.. using resistors/compoenents to filter out bad freq. in the signal..things we dont hear or ranges we dont want to?